protests began on 9/11 with protests in cairo and benghazi, libya. new concerns about a deadly disease spreading at one of our largest national parks. the outbreak of the hantavirus has infected 9 people, three of them have died. >> reporter: this is not the firsthan --this is not the firss outbreak here. but officials say the number of reported cases could rise. that's putting pressure on scientists to find a cure for this rare but deadly disease. yosemite national park is home to critters that carry potentially deadly diseases. now along with park maps, visitors are getting information about how to avoid the rodent-born illness while health officials look for clues in curry village where the mice were found living in the insulated walls. all but one of the cases originated in tent cabins. but why some people got sick and others didn't remains a mystery. >> the cases have been different cabins, different families. >> 23,000 campers may have been he can posed to the virus. epidemiologists want to know if the virus first identified in 1993 has mutated